* [Question] Regarding presence of duplicate ACPI CPU entries at two nodes \\_SB.CXXX and \\_SB.CPUS.CXXX of namespace
@ 2020-01-29 11:51 Salil Mehta
2020-01-29 12:23 ` Salil Mehta
0 siblings, 1 reply; 2+ messages in thread
From: Salil Mehta @ 2020-01-29 11:51 UTC (permalink / raw)
To: qemu-devel, qemu-arm
Cc: peter.maydell, drjones, sameo, mst, Linuxarm, eric.auger,
pbonzini, Igor Mammedov, lersek
Hello,
Observation:
If we launch Linux Guest VM using QEMU(running on any type host. I am using x86) with
CPU based on any ARM64 architecture then I could see QEMU populating ACPI nodes
related to same CPU at 2 places of the ACPI namespace:
1. \\_SB.CXXX
2. \\_SB.CPUS.CXXX
Above results in Guest VM showing duplicate CPU entries in the sysfs for the same CPUS.
I could make out the entries under \\_SB.CPUS.XXX are part of the container.
estuary:/$ ls -al /sys/bus/acpi/devices/
Observation 1: (belongs to \\_SB.C00X)
ACPI0007:00 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:00
ACPI0007:01 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:01
ACPI0007:02 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:02
ACPI0007:03 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:03
ACPI0007:04 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:04
ACPI0007:05 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:05
Observation 2: (belongs to \\_SB.CPUS.C00X and under container ACPI0010:00 part of \\_SB.CPUS)
ACPI0007:06 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:06
ACPI0007:07 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:07
ACPI0007:08 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:08
ACPI0007:09 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:09
ACPI0007:0a -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:0a
ACPI0007:0b -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:0b
ACPI0010:00 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00
estuary:/$ cat /sys/bus/acpi/devices/ACPI0010\:00/path
\_SB_.CPUS
estuary:/$ cat /sys/bus/acpi/devices/ACPI0007\:00/uid
0
estuary:/$ cat /sys/bus/acpi/devices/ACPI0007\:00/path
\_SB_.C000
estuary:/$ cat /sys/bus/acpi/devices/ACPI0007\:06/uid
0
estuary:/$ cat /sys/bus/acpi/devices/ACPI0007\:06/path
\_SB_.CPUS.C000
QEMU Code Excerpt:
I could trace with in QEMU AML code, the CPUS are being appended at 2 places:
Code 1. File: hw/arm/virt-acpi-build.c (Cause of Observation 1 i.e. \\_SB.CXXX )
static void acpi_dsdt_add_cpus(Aml *scope, int smp_cpus)
{
uint16_t i;
for (i = 0; i < smp_cpus; i++) { --->{should be possible cpus anyways}
Aml *dev = aml_device("C%.03X", i);
aml_append(dev, aml_name_decl("_HID", aml_string("ACPI0007")));
aml_append(dev, aml_name_decl("_UID", aml_int(i)));
aml_append(scope, dev);
}
}
Code 2. File: hw/acpi/cpu.c (Cause of Observation 2 i.e. \\_SB.CPUS.CXXX)
void build_cpus_aml(..)
{
[...]
cpus_dev = aml_device("\\_SB.CPUS");
{
[...]
/* build Processor object for each processor */
for (i = 0; i < arch_ids->len; i++) {
Aml *dev;
Aml *uid = aml_int(i);
GArray *madt_buf = g_array_new(0, 1, 1);
int arch_id = arch_ids->cpus[i].arch_id;
if (opts.acpi_1_compatible && arch_id < 255) {
dev = aml_processor(i, 0, 0, CPU_NAME_FMT, i);
} else {
dev = aml_device(CPU_NAME_FMT, i);
aml_append(dev, aml_name_decl("_HID", aml_string("ACPI0007")));
aml_append(dev, aml_name_decl("_UID", uid));
}
[...]
}
[...]
}
Questions:
Q1. I could not understand the purpose of keeping acpi_dsdt_add_cpus() after the code 2.
was introduced as part of the below change and which is already adding CPUS related
AML to \\_SB.CPUS namespace?
acpi: cpuhp: add CPU devices AML with _STA method
commit 5e1b5d93887b52eede156f846b6c4c5c8bbcfcdb
Q2. Do we really require CPUs being added by acpi_dsdt_add_cpus() in \\_SB.CXXX
Namespace OR is it a stray code left?
Please help to correct if there is a gap in my understanding here and please
forgive me if I have terribly missed out something very basic here.
Many thanks!
Best Regards
Salil
^ permalink raw reply [flat|nested] 2+ messages in thread
* RE: [Question] Regarding presence of duplicate ACPI CPU entries at two nodes \\_SB.CXXX and \\_SB.CPUS.CXXX of namespace
2020-01-29 11:51 [Question] Regarding presence of duplicate ACPI CPU entries at two nodes \\_SB.CXXX and \\_SB.CPUS.CXXX of namespace Salil Mehta
@ 2020-01-29 12:23 ` Salil Mehta
0 siblings, 0 replies; 2+ messages in thread
From: Salil Mehta @ 2020-01-29 12:23 UTC (permalink / raw)
To: Salil Mehta, qemu-devel, qemu-arm
Cc: peter.maydell, drjones, sameo, mst, Linuxarm, eric.auger,
Igor Mammedov, pbonzini, lersek
Please ignore this!
> From: Linuxarm [mailto:linuxarm-bounces@huawei.com] On Behalf Of Salil Mehta
> Sent: Wednesday, January 29, 2020 11:51 AM
> To: qemu-devel@nongnu.org; qemu-arm@nongnu.org
> Cc: peter.maydell@linaro.org; drjones@redhat.com; sameo@linux.intel.com;
> mst@redhat.com; Linuxarm <linuxarm@huawei.com>; eric.auger@redhat.com;
> pbonzini <pbonzini@redhat.com>; Igor Mammedov <imammedo@redhat.com>;
> lersek@redhat.com
> Subject: [Question] Regarding presence of duplicate ACPI CPU entries at two nodes
> \\_SB.CXXX and \\_SB.CPUS.CXXX of namespace
>
> Hello,
>
> Observation:
> If we launch Linux Guest VM using QEMU(running on any type host. I am using x86)
> with
> CPU based on any ARM64 architecture then I could see QEMU populating ACPI nodes
> related to same CPU at 2 places of the ACPI namespace:
> 1. \\_SB.CXXX
> 2. \\_SB.CPUS.CXXX
>
> Above results in Guest VM showing duplicate CPU entries in the sysfs for the
> same CPUS.
> I could make out the entries under \\_SB.CPUS.XXX are part of the container.
>
> estuary:/$ ls -al /sys/bus/acpi/devices/
>
> Observation 1: (belongs to \\_SB.C00X)
> ACPI0007:00 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:00
> ACPI0007:01 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:01
> ACPI0007:02 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:02
> ACPI0007:03 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:03
> ACPI0007:04 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:04
> ACPI0007:05 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0007:05
>
> Observation 2: (belongs to \\_SB.CPUS.C00X and under container ACPI0010:00 part
> of \\_SB.CPUS)
> ACPI0007:06
> -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:06
> ACPI0007:07
> -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:07
> ACPI0007:08
> -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:08
> ACPI0007:09
> -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:09
> ACPI0007:0a
> -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:0a
> ACPI0007:0b
> -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:0b
> ACPI0010:00 -> ../../../devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00
>
>
> estuary:/$ cat /sys/bus/acpi/devices/ACPI0010\:00/path
> \_SB_.CPUS
>
> estuary:/$ cat /sys/bus/acpi/devices/ACPI0007\:00/uid
> 0
> estuary:/$ cat /sys/bus/acpi/devices/ACPI0007\:00/path
> \_SB_.C000
>
> estuary:/$ cat /sys/bus/acpi/devices/ACPI0007\:06/uid
> 0
> estuary:/$ cat /sys/bus/acpi/devices/ACPI0007\:06/path
> \_SB_.CPUS.C000
>
>
>
> QEMU Code Excerpt:
> I could trace with in QEMU AML code, the CPUS are being appended at 2 places:
>
>
> Code 1. File: hw/arm/virt-acpi-build.c (Cause of Observation 1 i.e. \\_SB.CXXX )
>
> static void acpi_dsdt_add_cpus(Aml *scope, int smp_cpus)
> {
> uint16_t i;
>
> for (i = 0; i < smp_cpus; i++) { --->{should be possible cpus anyways}
> Aml *dev = aml_device("C%.03X", i);
> aml_append(dev, aml_name_decl("_HID", aml_string("ACPI0007")));
> aml_append(dev, aml_name_decl("_UID", aml_int(i)));
> aml_append(scope, dev);
> }
> }
>
>
> Code 2. File: hw/acpi/cpu.c (Cause of Observation 2 i.e. \\_SB.CPUS.CXXX)
>
> void build_cpus_aml(..)
> {
> [...]
> cpus_dev = aml_device("\\_SB.CPUS");
> {
> [...]
> /* build Processor object for each processor */
> for (i = 0; i < arch_ids->len; i++) {
> Aml *dev;
> Aml *uid = aml_int(i);
> GArray *madt_buf = g_array_new(0, 1, 1);
> int arch_id = arch_ids->cpus[i].arch_id;
>
> if (opts.acpi_1_compatible && arch_id < 255) {
> dev = aml_processor(i, 0, 0, CPU_NAME_FMT, i);
> } else {
> dev = aml_device(CPU_NAME_FMT, i);
> aml_append(dev, aml_name_decl("_HID",
> aml_string("ACPI0007")));
> aml_append(dev, aml_name_decl("_UID", uid));
> }
> [...]
> }
> [...]
> }
>
>
>
> Questions:
> Q1. I could not understand the purpose of keeping acpi_dsdt_add_cpus() after
> the code 2.
> was introduced as part of the below change and which is already adding CPUS
> related
> AML to \\_SB.CPUS namespace?
>
> acpi: cpuhp: add CPU devices AML with _STA method
> commit 5e1b5d93887b52eede156f846b6c4c5c8bbcfcdb
>
> Q2. Do we really require CPUs being added by acpi_dsdt_add_cpus() in \\_SB.CXXX
> Namespace OR is it a stray code left?
>
>
>
> Please help to correct if there is a gap in my understanding here and please
> forgive me if I have terribly missed out something very basic here.
>
> Many thanks!
>
> Best Regards
> Salil
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-01-29 11:51 [Question] Regarding presence of duplicate ACPI CPU entries at two nodes \\_SB.CXXX and \\_SB.CPUS.CXXX of namespace Salil Mehta
2020-01-29 12:23 ` Salil Mehta
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